Merge tag 'driver-core-5.8-rc1' of git://git.kernel.org/pub/scm/linux…

…/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the set of driver core patches for 5.8-rc1.

  Not all that huge this release, just a number of small fixes and
  updates:

   - software node fixes

   - kobject now sends KOBJ_REMOVE when it is removed from sysfs, not
     when it is removed from memory (which could come much later)

   - device link additions and fixes based on testing on more devices

   - firmware core cleanups

   - other minor changes, full details in the shortlog

  All have been in linux-next for a while with no reported issues"

* tag 'driver-core-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (23 commits)
  driver core: Update device link status correctly for SYNC_STATE_ONLY links
  firmware_loader: change enum fw_opt to u32
  software node: implement software_node_unregister()
  kobject: send KOBJ_REMOVE uevent when the object is removed from sysfs
  driver core: Remove unnecessary is_fwnode_dev variable in device_add()
  drivers property: When no children in primary, try secondary
  driver core: platform: Fix spelling errors in platform.c
  driver core: Remove check in driver_deferred_probe_force_trigger()
  of: platform: Batch fwnode parsing when adding all top level devices
  driver core: fw_devlink: Add support for batching fwnode parsing
  driver core: Look for waiting consumers only for a fwnode's primary device
  driver core: Move code to the right part of the file
  Revert "Revert "driver core: Set fw_devlink to "permissive" behavior by default""
  drivers: base: Fix NULL pointer exception in __platform_driver_probe() if a driver developer is foolish
  firmware_loader: move fw_fallback_config to a private kernel symbol namespace
  driver core: Add missing '\n' in log messages
  driver/base/soc: Use kobj_to_dev() API
  Add documentation on meaning of -EPROBE_DEFER
  driver core: platform: remove redundant assignment to variable ret
  debugfs: Use the correct style for SPDX License Identifier
  ...

Documentation/driver-api/driver-model/driver.rst

@@ -4,7 +4,6 @@ Device Drivers
 
 See the kerneldoc for the struct device_driver.
 
-
 Allocation
 ~~~~~~~~~~
 
@@ -167,9 +166,26 @@ the driver to that device.
 
 A driver's probe() may return a negative errno value to indicate that
 the driver did not bind to this device, in which case it should have
-released all resources it allocated::
+released all resources it allocated.
+
+Optionally, probe() may return -EPROBE_DEFER if the driver depends on
+resources that are not yet available (e.g., supplied by a driver that
+hasn't initialized yet).  The driver core will put the device onto the
+deferred probe list and will try to call it again later. If a driver
+must defer, it should return -EPROBE_DEFER as early as possible to
+reduce the amount of time spent on setup work that will need to be
+unwound and reexecuted at a later time.
+
+.. warning::
+      -EPROBE_DEFER must not be returned if probe() has already created
+      child devices, even if those child devices are removed again
+      in a cleanup path. If -EPROBE_DEFER is returned after a child
+      device has been registered, it may result in an infinite loop of
+      .probe() calls to the same driver.
+
+::
 
-	void (*sync_state)(struct device *dev);
+	void	(*sync_state)	(struct device *dev);
 
 sync_state is called only once for a device. It's called when all the consumer
 devices of the device have successfully probed. The list of consumers of the
@@ -212,6 +228,8 @@ over management of devices from the bootloader, the usage of sync_state() is
 not restricted to that. Use it whenever it makes sense to take an action after
 all the consumers of a device have probed::
 
+::
+
 	int 	(*remove)	(struct device *dev);
 
 remove is called to unbind a driver from a device. This may be
@@ -224,11 +242,15 @@ not. It should free any resources allocated specifically for the
 device; i.e. anything in the device's driver_data field.
 
 If the device is still present, it should quiesce the device and place
-it into a supported low-power state::
+it into a supported low-power state.
+
+::
 
 	int	(*suspend)	(struct device *dev, pm_message_t state);
 
-suspend is called to put the device in a low power state::
+suspend is called to put the device in a low power state.
+
+::
 
 	int	(*resume)	(struct device *dev);
 

drivers/base/base.h

@@ -153,6 +153,7 @@ extern char *make_class_name(const char *name, struct kobject *kobj);
 extern int devres_release_all(struct device *dev);
 extern void device_block_probing(void);
 extern void device_unblock_probing(void);
+extern void driver_deferred_probe_force_trigger(void);
 
 /* /sys/devices directory */
 extern struct kset *devices_kset;

drivers/base/core.c

@@ -49,6 +49,9 @@ static LIST_HEAD(wait_for_suppliers);
 static DEFINE_MUTEX(wfs_lock);
 static LIST_HEAD(deferred_sync);
 static unsigned int defer_sync_state_count = 1;
+static unsigned int defer_fw_devlink_count;
+static DEFINE_MUTEX(defer_fw_devlink_lock);
+static bool fw_devlink_is_permissive(void);
 
 #ifdef CONFIG_SRCU
 static DEFINE_MUTEX(device_links_lock);
@@ -529,7 +532,7 @@ static void device_link_add_missing_supplier_links(void)
 		int ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
 		if (!ret)
 			list_del_init(&dev->links.needs_suppliers);
-		else if (ret != -ENODEV)
+		else if (ret != -ENODEV || fw_devlink_is_permissive())
 			dev->links.need_for_probe = false;
 	}
 	mutex_unlock(&wfs_lock);
@@ -643,9 +646,17 @@ static void device_links_missing_supplier(struct device *dev)
 {
 	struct device_link *link;
 
-	list_for_each_entry(link, &dev->links.suppliers, c_node)
-		if (link->status == DL_STATE_CONSUMER_PROBE)
+	list_for_each_entry(link, &dev->links.suppliers, c_node) {
+		if (link->status != DL_STATE_CONSUMER_PROBE)
+			continue;
+
+		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+		} else {
+			WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
+			WRITE_ONCE(link->status, DL_STATE_DORMANT);
+		}
+	}
 }
 
 /**
@@ -684,11 +695,11 @@ int device_links_check_suppliers(struct device *dev)
 	device_links_write_lock();
 
 	list_for_each_entry(link, &dev->links.suppliers, c_node) {
-		if (!(link->flags & DL_FLAG_MANAGED) ||
-		    link->flags & DL_FLAG_SYNC_STATE_ONLY)
+		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
-		if (link->status != DL_STATE_AVAILABLE) {
+		if (link->status != DL_STATE_AVAILABLE &&
+		    !(link->flags & DL_FLAG_SYNC_STATE_ONLY)) {
 			device_links_missing_supplier(dev);
 			ret = -EPROBE_DEFER;
 			break;
@@ -949,11 +960,21 @@ static void __device_links_no_driver(struct device *dev)
 		if (!(link->flags & DL_FLAG_MANAGED))
 			continue;
 
-		if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER)
+		if (link->flags & DL_FLAG_AUTOREMOVE_CONSUMER) {
 			device_link_drop_managed(link);
-		else if (link->status == DL_STATE_CONSUMER_PROBE ||
-			 link->status == DL_STATE_ACTIVE)
+			continue;
+		}
+
+		if (link->status != DL_STATE_CONSUMER_PROBE &&
+		    link->status != DL_STATE_ACTIVE)
+			continue;
+
+		if (link->supplier->links.status == DL_DEV_DRIVER_BOUND) {
 			WRITE_ONCE(link->status, DL_STATE_AVAILABLE);
+		} else {
+			WARN_ON(!(link->flags & DL_FLAG_SYNC_STATE_ONLY));
+			WRITE_ONCE(link->status, DL_STATE_DORMANT);
+		}
 	}
 
 	dev->links.status = DL_DEV_NO_DRIVER;
@@ -1162,6 +1183,150 @@ static void device_links_purge(struct device *dev)
 	device_links_write_unlock();
 }
 
+static u32 fw_devlink_flags = DL_FLAG_SYNC_STATE_ONLY;
+static int __init fw_devlink_setup(char *arg)
+{
+	if (!arg)
+		return -EINVAL;
+
+	if (strcmp(arg, "off") == 0) {
+		fw_devlink_flags = 0;
+	} else if (strcmp(arg, "permissive") == 0) {
+		fw_devlink_flags = DL_FLAG_SYNC_STATE_ONLY;
+	} else if (strcmp(arg, "on") == 0) {
+		fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER;
+	} else if (strcmp(arg, "rpm") == 0) {
+		fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER |
+				   DL_FLAG_PM_RUNTIME;
+	}
+	return 0;
+}
+early_param("fw_devlink", fw_devlink_setup);
+
+u32 fw_devlink_get_flags(void)
+{
+	return fw_devlink_flags;
+}
+
+static bool fw_devlink_is_permissive(void)
+{
+	return fw_devlink_flags == DL_FLAG_SYNC_STATE_ONLY;
+}
+
+static void fw_devlink_link_device(struct device *dev)
+{
+	int fw_ret;
+
+	if (!fw_devlink_flags)
+		return;
+
+	mutex_lock(&defer_fw_devlink_lock);
+	if (!defer_fw_devlink_count)
+		device_link_add_missing_supplier_links();
+
+	/*
+	 * The device's fwnode not having add_links() doesn't affect if other
+	 * consumers can find this device as a supplier.  So, this check is
+	 * intentionally placed after device_link_add_missing_supplier_links().
+	 */
+	if (!fwnode_has_op(dev->fwnode, add_links))
+		goto out;
+
+	/*
+	 * If fw_devlink is being deferred, assume all devices have mandatory
+	 * suppliers they need to link to later. Then, when the fw_devlink is
+	 * resumed, all these devices will get a chance to try and link to any
+	 * suppliers they have.
+	 */
+	if (!defer_fw_devlink_count) {
+		fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
+		if (fw_ret == -ENODEV && fw_devlink_is_permissive())
+			fw_ret = -EAGAIN;
+	} else {
+		fw_ret = -ENODEV;
+	}
+
+	if (fw_ret == -ENODEV)
+		device_link_wait_for_mandatory_supplier(dev);
+	else if (fw_ret)
+		device_link_wait_for_optional_supplier(dev);
+
+out:
+	mutex_unlock(&defer_fw_devlink_lock);
+}
+
+/**
+ * fw_devlink_pause - Pause parsing of fwnode to create device links
+ *
+ * Calling this function defers any fwnode parsing to create device links until
+ * fw_devlink_resume() is called. Both these functions are ref counted and the
+ * caller needs to match the calls.
+ *
+ * While fw_devlink is paused:
+ * - Any device that is added won't have its fwnode parsed to create device
+ *   links.
+ * - The probe of the device will also be deferred during this period.
+ * - Any devices that were already added, but waiting for suppliers won't be
+ *   able to link to newly added devices.
+ *
+ * Once fw_devlink_resume():
+ * - All the fwnodes that was not parsed will be parsed.
+ * - All the devices that were deferred probing will be reattempted if they
+ *   aren't waiting for any more suppliers.
+ *
+ * This pair of functions, is mainly meant to optimize the parsing of fwnodes
+ * when a lot of devices that need to link to each other are added in a short
+ * interval of time. For example, adding all the top level devices in a system.
+ *
+ * For example, if N devices are added and:
+ * - All the consumers are added before their suppliers
+ * - All the suppliers of the N devices are part of the N devices
+ *
+ * Then:
+ *
+ * - With the use of fw_devlink_pause() and fw_devlink_resume(), each device
+ *   will only need one parsing of its fwnode because it is guaranteed to find
+ *   all the supplier devices already registered and ready to link to. It won't
+ *   have to do another pass later to find one or more suppliers it couldn't
+ *   find in the first parse of the fwnode. So, we'll only need O(N) fwnode
+ *   parses.
+ *
+ * - Without the use of fw_devlink_pause() and fw_devlink_resume(), we would
+ *   end up doing O(N^2) parses of fwnodes because every device that's added is
+ *   guaranteed to trigger a parse of the fwnode of every device added before
+ *   it. This O(N^2) parse is made worse by the fact that when a fwnode of a
+ *   device is parsed, all it descendant devices might need to have their
+ *   fwnodes parsed too (even if the devices themselves aren't added).
+ */
+void fw_devlink_pause(void)
+{
+	mutex_lock(&defer_fw_devlink_lock);
+	defer_fw_devlink_count++;
+	mutex_unlock(&defer_fw_devlink_lock);
+}
+
+/** fw_devlink_resume - Resume parsing of fwnode to create device links
+ *
+ * This function is used in conjunction with fw_devlink_pause() and is ref
+ * counted. See documentation for fw_devlink_pause() for more details.
+ */
+void fw_devlink_resume(void)
+{
+	mutex_lock(&defer_fw_devlink_lock);
+	if (!defer_fw_devlink_count) {
+		WARN(true, "Unmatched fw_devlink pause/resume!");
+		goto out;
+	}
+
+	defer_fw_devlink_count--;
+	if (defer_fw_devlink_count)
+		goto out;
+
+	device_link_add_missing_supplier_links();
+	driver_deferred_probe_force_trigger();
+out:
+	mutex_unlock(&defer_fw_devlink_lock);
+}
 /* Device links support end. */
 
 int (*platform_notify)(struct device *dev) = NULL;
@@ -2364,36 +2529,6 @@ static int device_private_init(struct device *dev)
 	return 0;
 }
 
-static u32 fw_devlink_flags;
-static int __init fw_devlink_setup(char *arg)
-{
-	if (!arg)
-		return -EINVAL;
-
-	if (strcmp(arg, "off") == 0) {
-		fw_devlink_flags = 0;
-	} else if (strcmp(arg, "permissive") == 0) {
-		fw_devlink_flags = DL_FLAG_SYNC_STATE_ONLY;
-	} else if (strcmp(arg, "on") == 0) {
-		fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER;
-	} else if (strcmp(arg, "rpm") == 0) {
-		fw_devlink_flags = DL_FLAG_AUTOPROBE_CONSUMER |
-				   DL_FLAG_PM_RUNTIME;
-	}
-	return 0;
-}
-early_param("fw_devlink", fw_devlink_setup);
-
-u32 fw_devlink_get_flags(void)
-{
-	return fw_devlink_flags;
-}
-
-static bool fw_devlink_is_permissive(void)
-{
-	return fw_devlink_flags == DL_FLAG_SYNC_STATE_ONLY;
-}
-
 /**
  * device_add - add device to device hierarchy.
  * @dev: device.
@@ -2426,9 +2561,8 @@ int device_add(struct device *dev)
 	struct device *parent;
 	struct kobject *kobj;
 	struct class_interface *class_intf;
-	int error = -EINVAL, fw_ret;
+	int error = -EINVAL;
 	struct kobject *glue_dir = NULL;
-	bool is_fwnode_dev = false;
 
 	dev = get_device(dev);
 	if (!dev)
@@ -2526,11 +2660,6 @@ int device_add(struct device *dev)
 
 	kobject_uevent(&dev->kobj, KOBJ_ADD);
 
-	if (dev->fwnode && !dev->fwnode->dev) {
-		dev->fwnode->dev = dev;
-		is_fwnode_dev = true;
-	}
-
 	/*
 	 * Check if any of the other devices (consumers) have been waiting for
 	 * this device (supplier) to be added so that they can create a device
@@ -2539,19 +2668,13 @@ int device_add(struct device *dev)
 	 * This needs to happen after device_pm_add() because device_link_add()
 	 * requires the supplier be registered before it's called.
 	 *
-	 * But this also needs to happe before bus_probe_device() to make sure
+	 * But this also needs to happen before bus_probe_device() to make sure
 	 * waiting consumers can link to it before the driver is bound to the
 	 * device and the driver sync_state callback is called for this device.
 	 */
-	device_link_add_missing_supplier_links();
-
-	if (fw_devlink_flags && is_fwnode_dev &&
-	    fwnode_has_op(dev->fwnode, add_links)) {
-		fw_ret = fwnode_call_int_op(dev->fwnode, add_links, dev);
-		if (fw_ret == -ENODEV && !fw_devlink_is_permissive())
-			device_link_wait_for_mandatory_supplier(dev);
-		else if (fw_ret)
-			device_link_wait_for_optional_supplier(dev);
+	if (dev->fwnode && !dev->fwnode->dev) {
+		dev->fwnode->dev = dev;
+		fw_devlink_link_device(dev);
 	}
 
 	bus_probe_device(dev);